import { Injectable, Renderer2, RendererFactory2 } from '@angular/core';
import { InlineSVGDirective } from './inline-svg.directive';
import { SVGScriptEvalMode } from './inline-svg.config';

@Injectable({
  providedIn: 'root'
})
export class InlineSVGService {

  private _renderer: Renderer2;
  private _ranScripts: { [url: string]: boolean } = {};

  constructor(rendererFactory: RendererFactory2) {
    this._renderer = rendererFactory.createRenderer(null, null);
  }

  insertEl(
    dir: InlineSVGDirective,
    parentEl: HTMLElement,
    content: Element,
    replaceContents: boolean,
    prepend: boolean) {
    if (replaceContents && !prepend) {
      const parentNode = dir._prevSVG && dir._prevSVG.parentNode;
      if (parentNode) {
        this._renderer.removeChild(parentNode, dir._prevSVG);
      }

      parentEl.innerHTML = '';
    }

    if (prepend) {
      this._renderer.insertBefore(parentEl, content, parentEl.firstChild);
    } else {
      this._renderer.appendChild(parentEl, content);
    }

    if (content.nodeName === 'svg') {
      dir._prevSVG = content as SVGElement;
    }
  }

  /**
   * Executes scripts from within the SVG.
   * Based off of code from https://github.com/iconic/SVGInjector
   *
   * @param svg SVG with scripts to evaluate.
   * @param url URL from which the SVG was loaded from.
   * @param evalMode Evaluation mode. Can be one of "always", "once", or "none".
   */
  evalScripts(svg: SVGElement, url: string, evalMode: string): void {
    const scripts = svg.querySelectorAll('script');
    const scriptsToEval = [];

    // Fetch scripts from SVG
    for (let i = 0; i < scripts.length; i++) {
      const scriptType = scripts[i].getAttribute('type');

      if (!scriptType || scriptType === 'application/ecmascript' || scriptType === 'application/javascript') {
        const script = scripts[i].innerText || scripts[i].textContent;
        scriptsToEval.push(script);
        this._renderer.removeChild(scripts[i].parentNode, scripts[i]);
      }
    }

    // Run scripts in closure as needed
    if (scriptsToEval.length > 0 && (evalMode === SVGScriptEvalMode.ALWAYS ||
      (evalMode === SVGScriptEvalMode.ONCE && !this._ranScripts[url]))) {
      for (let i = 0; i < scriptsToEval.length; i++) {
        new Function(scriptsToEval[i])(window);
      }

      this._ranScripts[url] = true;
    }
  }

}